This invention relates to vehicle loudspeakers, which may be used, for example, in in-vehicle hands-free communication systems such as telephone systems, and which may also be used in in-vehicle entertainment systems.
One disadvantage of an in-vehicle hands-free telephone system which uses conventional loudspeakers is that the microphone and loudspeaker need to be, or are typically, widely separated. Typically, the microphone is attached to the windscreen pillar so as to be relatively close to the driver""s mouth, whilst the loudspeaker is placed in the foot-well on the passenger side, i.e. on the other side of the driver to the microphone. This can cause an unwanted strain in a telephone conversation, because it is instinctive for the driver to turn towards the sound source, i.e. the foot-well loudspeaker, and away from the microphone. This therefore reduces the signal-to-noise ratio at the microphone and consequently reduces the conversation quality. Also, the driver may be distracted from looking straight forward, thus reducing the overall safety of the vehicle and its occupants.
In accordance with a first aspect of the present invention, there is provided an attachment for a vehicle sun visor, the attachment being characterised by: a panel which can be vibrated to generate sound; a piezo-electric actuator coupled to the panel and operable to vibrate the panel in response to a driving signal so as to act as a loudspeaker; and means for attaching the panel to the sun visor.
In accordance with a second aspect of the present invention, there is provided a sun visor for a vehicle, comprising: a panel; and means for attaching the panel to the vehicle adjacent an upper edge of a windscreen of the vehicle; characterized in that: the panel is vibratable to generate sound; and a piezo-electric actuator is coupled to the panel and is operable to vibrate the panel in response to a driving signal so as to act as a loudspeaker.
By providing the loudspeaker as part of a vehicle sun visor, or as an attachment to a vehicle sun visor, the loudspeaker can be placed relatively close to the driver""s ears and in front of the driver. Accordingly, there will not be any significant tendency for the driver to turn their head when listening to the loudspeaker. Also, by using a panel, such as a flat panel, which is driven by a piezo-electric actuator, as the loudspeaker, an extremely thin construction can be realised, and the loudspeaker can conveniently be integrated into a sun visor, or be provided as an unobtrusive attachment for a sun visor, in such a way that there is little likelihood of the sun visor or attachment causing any greater injury to the driver in the event of an accident than a conventional sun visor.
In one embodiment of the first aspect of the invention, the attaching means is arranged to one side of the panel for attaching the panel to the vehicle sun visor with said one side of the panel facing the sun visor.
In another embodiment of the first aspect of the invention, the attaching means comprises: a second panel hinged to the first-mentioned panel; and means for biasing the panels towards each other so that they can grip the vehicle sun visor therebetween. In this case, the attachment may further include a second piezo-electric actuator coupled to the second panel and operable to vibrate the second panel in response to the, or a further, driving signal so as to act as a second loudspeaker.
The sun visor of the second aspect of the invention may further include a second panel generally parallel to the first-mentioned panel; the first-mentioned piezo-electric actuator, or a second piezo-electric actuator, being coupled to the second panel and operable to vibrate the second panel in response to the, or a further, driving signal so as to act as a second loudspeaker.
In the case where the attachment or the vehicle sun visor has two loudspeakers, the first-mentioned loudspeaker and the second loudspeaker may have substantially different frequency response characteristics. Accordingly, the two loudspeakers can be designed to provide a better overall frequency response.
The attachment or vehicle sun visor may further include a microphone.
In accordance with a third aspect of the present invention, there is provided a vehicle hands-free telephone system having a loudspeaker and a microphone, characterized in that the loudspeaker is provided by a vehicle sun visor attachment, or a vehicle sun visor, according to the first or second aspect of the invention.
The microphone of the telephone system is preferably provided by the mnicrophone of the attachment or sun visor.
In accordance with a fourth aspect of the present invention, there is provided a vehicle having at least one of: (a) a sun visor, and an attachment therefor according to the first aspect of the invention; (b) a sun visor according to the second aspect of the invention; and (c) a telephone system according to the third aspect of the invention.